1. Technical Field
The present invention relates to a force detector and a robot.
2. Related Art
Recently, introduction of industrial robots to production facilities including factories has been promoted for improvement in production efficiency. As the industrial robots, machine tools for machining parent materials such aluminum boards are representative. Some machine tools include force detectors that detect forces on the parent materials at machining (for example, see Patent Document 1 (JP-2013-130431)).
Patent Document 1 discloses a sensor device including a piezoelectric element, a ceramic package having a recessed part for housing the piezoelectric element, and a lid joined to the ceramic package to close the opening of the recessed part with the piezoelectric element housed within the recessed part of the ceramic package. Further, the sensor device is sandwiched by two pressurization plates.
In the sensor device, when an external force is applied to the pressurization plate, the external force is transmitted to the piezoelectric element via the ceramic package and the lid, the piezoelectric element outputs electric charge in response to the external force, and thereby, the applied external force may be detected based on the electric charge.
Further, the sensor device is air-tightly sealed by the ceramic package and the lid and shielded from outside air. Thereby, the electric charge generated from the piezoelectric element is prevented from unintendedly leaking to the outside due to moisture or the like.
However, in the force detector disclosed in Patent Document 1, there is a problem that external forces are repeatedly applied to the pressurization plates, and thereby, stress is repeatedly applied to the ceramic package and the ceramic package is broken. Accordingly, it is difficult to use the force detector stably over a long period.
Further, in the force detector, there is another problem that, at manufacturing, when the sensor device is sandwiched by the pressurization plates, the ceramic package is broken due to the pressure applied by the pressurization plates.